What distinguishes solid construction and design from an M.C. Escher optical illusion? Accurate measurements.In SketchUp, the Tape Measure tool, the Protractor tool, and the Measurements box enable you to model precisely:With the Tape Measure tool (), you can measure a distance and set precise guide lines or guide points.  

In SketchUp, you can resize and reshape your model based on the relative sizes of your edges and faces. Here's a quick overview of the available options: